Adds part08 illustrates Vec and iterators

codes/rust_lang/part08/Cargo.toml

codes/rust_lang/part08/src/custom_int.rs

codes/rust_lang/part08/src/io.rs

codes/rust_lang/part08/src/lib.rs

codes/rust_lang/part08/src/main.rs

codes/rust_lang/part08/src/minimum.rs

codes/rust_lang/part08/src/something_or_nothing.rs